Looking for a way to merge a path onto a path

[Horseflesh]

This is kind of a weird question but it would be SO helpful if I could figure out a trick to do this...

I have some "one line" fonts which are intended to make paths for laser engravers or other CNC machines. Unfortunately, to make the best use of these fonts, you need special (expensive) software to render them as actual single-line paths. Normal design tools like Illustrator and AD mangle these fonts in a variety of ways, as outline fonts aren't supposed to have open paths (as I understand it). 

Here's an example of what I mean. The "a" glyph looks like it's drawn with one line... but if you use the Node tool and pull at the nodes, you can see it is actually a closed path with 2 copies of every node. 

My laser cutter would not draw one graceful one-line "a" if I fed it this art. What I want to do is convert this to a single open path as if I drew that "a" with the pen tool. And ideally that would be through some clever few menu operations that I could apply to a big group of shapes... so I can type, convert to curves, and then process to make the text all true single-line. 

Does anyone have any ideas? 

The font pictured above is #6 from this page, but they all misbehave in similar ways.

http://www.mrrace.com/CamBam_Fonts/

 

[Pšenda]

Export to bitmap image (PNG with high resolution), and try convert back to vector (for example https://www.vectorizer.io). 

[PixelPest]

You´ll need an centerline autotracer - otherwise you´ll always get a filled path as a result. I don´t think vectorizer.io supports this feature like SuperVectorizer.

I have a few CNC-fonts but all convert keys into at least a double line - which may cause extra processing time. 

Cheers